The Epidemiology Branch (EBRP) is designing a case control study to examine the effect of vitamin-folate supplements in the periconceptional period and neural tube defect risk. Drs. Mills and Rhoads are planning a telephone interview study in which mothers who have delivered a child with a neural tube defect (defined as cases), mothers who have delivered a child with another malformation (defined as controls), and mothers who have delivered a normal child (defined as controls) will be compared on the use of vitamins in the period around conception. A request for contracts is currently in preparation.